With the development of mobile communication technologies, mobile terminals such as mobile phones, tablet computers, or the like, are used more and more widely. Mobile terminals normally use antenna systems to convert electric power into radio waves, and vice versa, for realizing wireless transmission and reception. One of important components in an antenna system is an antenna radiator (namely, a radiating part), which is typically arranged on an inner surface of a back cover of a mobile terminal.
Mobile terminals with metal shells, for example, metal back covers, are become more and more popular because of fashion appearance as well as good durability. However, the metal back cover may cause the radio waves be shielded from the radiating part of the antenna system, and thus a radiation efficiency of the antenna system is very low. As such, the antenna system is incapable of performing normal transmission and reception for wireless signals.
Therefore, it is necessary to provide a new antenna system which can overcome the aforesaid problems.